Antimicrobial Activity of Commercial Photocatalytic SaniTise (TM) Window Glass

Photocatalytic and antibacterial properties of TiO2-based SaniTise (TM) glass by Pilkington were studied with an aim to benchmark this first commercial UVA-activated antimicrobial glass and to evaluate its efficacy in indoor-like conditions. For comparison, the antibacterial and photocatalytic activity of self-cleaning BIOCLEAN(R) glass and photocatalytically inactive clear float PLANICLEAR(R) control glass were analysed. The presence of an anatase TiO2 layer was demonstrated on the surface of SaniTise (TM) and BIOCLEAN(R). Photocatalytic degradation of organic model dye and antibacterial activity against Escherichia coli and Staphylococcus aureus were higher on SaniTise (TM) than on BIOCLEAN(R). In a liquid antibacterial assay corresponding to ISO 27447 format, 4 h exposure of bacteria to the SaniTise (TM) surface under UVA resulted in > 2.8 log decrease in E. coli and > 2.5 log decrease in S. aureus viable cell counts. In experiments with the more application-relevant "dry droplet method ", significantly higher antibacterial activity was observed up to the level where during 4 h at & LE;50% RH complete inactivation of bacteria was observed also on PLANICLEAR(R)control glass. The latter raises concerns about the real-life relevancy of the standard test conditions and suggests that at low air humidity conditions, shorter exposure periods than suggested by current antimicrobial testing protocols should be targeted by photocatalytically active antibacterial surfaces.